KR101101089B1 - Method and apparatus for power line communication - Google Patents

Abstract

The variation cycle L of the characteristics of the transmission line is divided into a plurality of sections, and the evaluation of the transmission line only in one of the n sections is repeated within one beacon period, so that the transmission line evaluation is performed for all n sections. Is performed. The beacon period T is set based on T = L × m / n when n is an integer of 2 or more, m is an integer of n or more, and the greatest common divisor with n is 1.

Description

Power line communication device and method {METHOD AND APPARATUS FOR POWER LINE COMMUNICATION}

The present invention relates to a communication apparatus and a transmission line evaluation method. More particularly, the present invention relates to a communication device for transmitting and receiving data based on characteristics of transmission lines between devices without degrading throughput, and a transmission line evaluation method (channel estimation) performed by the communication device, This is precisely estimated and evaluated.

In a communication method in which communication parameters such as subcarriers and modulation methods used for transmission and reception are determined based on evaluation of characteristics of a transmission line, it is important to accurately determine communication parameters suitable for characteristics of the transmission line in transmission. In particular, multi-carrier transmission line methods using subcarriers and modulation methods suitable for the characteristics of a transmission line in a communication system having attenuation characteristics that vary greatly with frequency (for example, power line carrier communication including a power line as a communication medium). It is effective to use

In a transmission line evaluation method used in a conventional communication system, a transmission line is evaluated periodically or when the number of times of retransmission due to a communication error is more than a set value (in consideration of deterioration of characteristics of the transmission line). Then, based on the result of this evaluation for the transmission line, a new parameter is selected and data is transmitted and received. Such a technique is disclosed, for example, in Japanese Laid-Open Patent Publication No. 2002-158675A.

However, in an environment where the characteristics of the transmission line change periodically, communication parameters are often suitable for the characteristics of the transmission line during data transmission unless the timing of the data sending the selected communication parameter in the transmission line evaluation is synchronized with the periodic change in the transmission line characteristic. Not. Therefore, in the conventional method described above, the maximum communication efficiency is not always obtained even when the transmission line is evaluated.

Therefore, the following method has been conventionally proposed as a countermeasure against this problem.

First, the fluctuation cycle of the transmission line is synchronized with the frame period of the communication system, which is divided into a plurality of sections. Then, within one frame period, the plurality of divided sections of the transmission line are continuously evaluated section by section. Next, as a result of the evaluation of the transmission line, the communication parameters obtained in the section with the highest communication efficiency are selected and then communication is performed. Fig. 12 is a diagram showing the operation procedure of the conventional transmission line evaluation method.

However, in the conventional method shown in Fig. 12, the transmission line continues to be evaluated and thus requests transmission line evaluation and the response message occupies the transmission line, so that the transmission of stream data, audio data, or other data to be transmitted is made. There is a problem that prevents communication. Further, in this conventional method, the time from the start of the frame period of the communication system to the start of the transmission line evaluation section is different for each frame period. As a result, when the band is guaranteed by time division, for example, scheduling for transmission line evaluation is not only complicated, but also a scheduling condition cannot be satisfied.

It is therefore an object of the present invention to provide a communication apparatus for evaluating a transmission line in a simple scheduling manner so that the characteristics of the transmission line can be evaluated very accurately, and that data can be transmitted and received at high throughput without affecting other streams. To provide a method for evaluating a transmission line performed by the communication device.

The present invention is applied to a communication device that performs periodic communication with another communication device through a transmission line. In order to achieve the above object, a communication apparatus of the present invention includes a communication control unit, a transmission line evaluation unit, and a communication parameter determination unit.

The communication control unit sets the communication period for performing communication to " L × m / n " Set to). The transmission line evaluator evaluates the characteristics of the transmission line within (L / n) time after the start of the communication period and after a certain offset time L × k / n (k is an integer of 0 or more). The communication parameter determining unit determines the communication parameter used by the communication control unit based on the evaluation result of the transmission line evaluation unit.

Preferably, the transmission line evaluator evaluates the transmission line characteristics n or more times. In addition, the characteristics of the transmission line are evaluated when the detection of a change in state of the transmission line is first started. The communication period is a period of a beacon sent from a communication device serving as a master unit. If there is a request for time allocation for evaluating the characteristics of the transmission line, the communication device sends a time allocation request for evaluating the characteristics of the transmission line to a communication device functioning as a master unit, and the transmission line characteristic is evaluated only during the time period for which the approval is given. do. If this time allocation is notified from the communication device functioning as the master unit using a beacon frame or polling frame, the characteristics of the transmission line are only evaluated during the time given the grant. The variation cycle L of the characteristics of the transmission line is 1/2 of the commercial power supply cycle.

The process performed by each configuration of each communication device described above can be considered a transmission line evaluation method that provides a series of progression. This method is provided in a programmed form as a series of processes performed on a computer. The program may be published on a computer in a form stored on a computer readable storage medium. In addition, some of the functional blocks described above constitute a communication device that can be realized as an LSI which is an integrated circuit.

As described above, according to the present invention, the transmission line is evaluated in a distributed manner by a simple schedule, so that the characteristics of the transmission line are evaluated with high accuracy and this data can be transmitted and received without the influence of other flows even at high throughput. Can be.

1 is a diagram showing an example of the configuration of a communication network system using a communication device according to a first embodiment of the present invention;

2 is a diagram showing an example of a timing at which a transmission line is evaluated by the communication device according to the first embodiment of the present invention;

3 is a view showing a timing example in which a transmission line is evaluated by the communication device according to the first embodiment of the present invention;

4 is a diagram showing an example of a timing at which a transmission line is evaluated by the communication device according to the first embodiment of the present invention;

5 is a communication sequence showing a process in which a transmission line is evaluated by the communication device according to the first embodiment of the present invention;

6 is a diagram illustrating an example of a tone map;

7 is a diagram for explaining a relationship between noise and a transmission line evaluation section;

8 is another communication sequence showing a process in which a transmission line is evaluated by the communication device according to the first embodiment of the present invention;

9 is a view for explaining how a beacon period is determined by a communication device according to the first embodiment of the present invention;

10 is a view for explaining a method in which a beacon period is determined by a communication device according to the first embodiment of the present invention;

11 is a view showing an embodiment of a communication network system of a communication device in which the communication device of the present invention is applied to a high speed power line transmission line; and

12 is a communication sequence diagram illustrating a process in which a transmission line is evaluated by a conventional communication apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First embodiment

1 is a diagram showing an example of the configuration of a communication network system using the communication device 1 according to the first embodiment of the present invention. In Fig. 1, a plurality of communication devices 1 in the communication network system of the present invention are connected to each other by a transmission line 2. The transmission line 2 may be configured by wire or wirelessly. This embodiment is an example, in which one of the plurality of communication devices 1 is a master unit which periodically transmits a beacon for controlling communication of another communication device 1 (slave unit). It will be described using a communication network system.

The communication device 1 is composed of a communication control unit 11, a transmission line evaluating unit 12, and a communication parameter determining unit 13. The communication control unit 11 handles most communication processes performed by the communication device 1. Basically, the communication control unit 11 performs communication with another communication device 1 using the communication parameter determined by the communication parameter determining unit 13. The transmission line evaluating unit 12 evaluates the characteristics of the transmission line 2 at a predetermined periodic timing and evaluates the state of the transmission line 2. The communication parameter determining unit 13 sets or updates communication parameters in accordance with the result obtained when the transmission line evaluating unit 12 evaluates the transmission line 2.

Hereinafter, a method in which the communication device 1 configured as described above evaluates the characteristics of the transmission line is described. 2 to 4 respectively show examples of timings at which the communication device 1 evaluates a transmission line according to an embodiment of the present invention. 5 is a communication sequence illustrating a process of evaluating a transmission line by the communication device 1 according to an embodiment of the present invention.

In this embodiment, the case where the noise of a specific pattern (X in Fig. 2) is generated at specific intervals as shown in Fig. 2 in the transmission line 2 in the communication network system is described. Corresponds to the cycle of variation of the characteristics. In this case, the communication control part 11 of each communication apparatus 1 which comprises a communication network system sets the beacon period which becomes a communication period as follows. Here, the beacon period is the time interval between when the beacon is transmitted by the master unit and when the next beacon is transmitted.

Due to the influence of the power circuit of a household electric appliance connected to the power line, the cycle of the power line noise pattern may be equal to 1/2 of the cycle of the commercial voltage (50 Hz or 60 Hz). Therefore, when the communication network system uses the power line, it is necessary to consider the characteristics of the transmission line that tunes to 1/2 cycle of the commercial power supply as described above (see sine wave in Fig. 2).

The set point is a cycle in which the variation cycle (L) of the transmission line characteristics is divided into n sets of sections (n sections), and the transmission line evaluation is performed only for one of the n sections of one beacon period, and this transmission line is repeated. Evaluation is performed for all n sections. The beacon period T that implements this point is set based on “T = L × m / n”, where n is an integer of 2 or more, m is an integer of n or more, and the greatest common divisor is n. 1 Further, the offset time is set based on "L x k / n" when k is a real number of 0≤k <m. In this way, when the offset time is set to evaluate transmission lines on a section-by-section basis within one beacon period, it is possible to quickly deal with variations in transmission lines. Offset time can be freely set without taking into account dealing quickly with variations in the transmission line.

2 and 3 show examples when n = 3 and m = 17. 4 is an embodiment where n = 4 and m = 19. When the communication network system uses a power line as described above, the beacon period T uses L = 8.333 msec when the frequency of the commercial power is 60 Hz, and L = 10 msec when the frequency of the commercial power is 50 Hz. It is calculated. 2 to 4, the description of the beacon itself is omitted. In addition, considering the offset time, k = 16 in FIG. 2, k = 15 in FIG. 3, and k = 17 in FIG. 4. As shown in Figs. 2 to 4, when setting the beacon period and the offset time based on the aforementioned points, after the offset time has elapsed, each transmission line evaluation section does not have the same timing as the commercial power cycle, Depart from Therefore, it is easy to realize transmission line evaluation which is continuous in time without overlapping with a commercial power cycle.

In FIG. 5, the process of evaluating the transmission line by the communication device 1 will be described in detail in sequence.

At initial startup, such as when detecting changes in power input or characteristics of a transmission line, a communication device (1; hereafter referred to as device A) acting as a slave unit is a communication device (hereinafter referred to as device C) acting as a master unit. Request a time allocation to evaluate the transmission line (step 1). Upon receiving a time allocation request for transmission line evaluation from device A, device C transmits a beacon plus information about the time allocated for transmission line evaluation during the next time for beacon transmission (step 2). This information about the time allocated for transmission line evaluation represents information showing a section that can be used for transmission line evaluation and is generally given as an offset time from the start time of the beacon period.

When receiving a beacon from the device C plus the time allocation information for transmission line evaluation, after the beacon period starts, after the offset time, the device A evaluates the characteristics of the transmission line based on this information. In the example of FIG. 2, the characteristics of the transmission line are evaluated in transmission line evaluation section 2/3 (half-tone part 2 of the figure). A specific method for evaluating the characteristics of a transmission line is to request transmission line evaluation from a communication device (hereinafter referred to as device B) that device A operates as a slave unit, and sends a response from the device B to the evaluation request of the transmission line. Receive (step 4). Evaluation of such a transmission line is performed in the following manner, for example.

First, not only the transmission line evaluation request, but also a predetermined series of evaluations are transmitted from the device A to the device B. Based on the series of evaluations, device B calculates a received carrier to noise power ratio (CNR). Then, according to the calculated received CNR, the device B creates a tone map that clarifies communication parameters such as subcarriers to be used and modulation methods for each subcarrier. One embodiment of the tone map is shown in FIG. Here, the tone map is composed of a tone map number that distinguishes the tone map from other tone maps, a subcarrier number indicating the subcarrier in the tone map, and information on the use / nonuse of the subcarrier and the modulation factor. The information on the subcarrier modulation factor may include information about the modulation type (eg, 16 QAM or 32 QAM) or the number of subcarrier allocation bits (eg, “4” when 16QAM), as shown in FIG. 6. Can be Device B then responds to Device A by sending a transmission line evaluation including the tonemap. The multi-transmitter transmission method described above can also be used as another method, such as the spread spectrum method as an embodiment. In addition, information on the received CNR is used to determine communication parameters, but other information may also be used.

In a similar manner, device A evaluates the transmission line characteristics in another transmission line evaluation section (steps 5 to 10). In the embodiment of Fig. 2, the characteristics of the transmission line are the transmission line evaluation section 1/3 (half-tone portion 1 in the figure) and the transmission line evaluation section 3/3 (half-tone portion in the figure). 3)). In this way, the device A completes transmission line evaluation, i.e., acquisition of the tonemap, for all of these three separate transmission line evaluation sections (step 11). Of the following plurality of necessary tone maps, the device A informs the selection device B which tone map is optimal for use in communication (step 12). In this way, devices A and B share an optimal top map. Thereafter, communication is performed using this optimal tonemap.

The optimal tonemap is chosen in the following way, for example. In the example of FIG. 2, noise occurs in transmission line evaluation sections 1/3 and 2/3, and noise does not occur in transmission line evaluation section 3/3 (see FIG. 7, partially extracted and enlarged in FIG. 2). . Therefore, the tonemap of transmission line evaluation section 3/3 has the highest PHY rate. Therefore, this tonemap with the highest PHY rate is chosen as the tonemap used for communication.

Even if all tonemaps in the transmission line evaluation section are not obtained, it is possible to select an optimal tonemap from the tonemaps obtained when the set timeout time has elapsed.

As described above, according to the communication apparatus 1 of one embodiment of the present invention, it is easy to realize transmission line evaluation in a distributed manner. Therefore, the characteristics of the transmission line can be accurately evaluated, and thus the data transmission / reception throughput can be increased.

In the first embodiment, the integers n and m are described as fixed values, but n and m are dynamic depending on the change of the transmission line based on, for example, the evaluation result of the transmission line, the PHY speed value, or the degree of change of the PHY speed. Can be changed to

Also, although no related devices other than devices A, B, and C are shown in the communication sequence shown in FIG. 4, the process is typically performed as shown in FIG. 8.

Referring to FIG. 8, time allocation information for transmission line evaluation is added to the beacon delivered from device C. For device A, the time allocation information for the transmission line evaluation not only specifies the time that the transmission line evaluation request can be sent to device B, but also prohibits devices B, C and other devices from passing data. . By prohibiting the transmission of devices other than the device sending the request at the time when the transmission line evaluation request is sent (half-tone period in FIG. 8), for example, a collision between the transmission line evaluation request and the data is prevented. It can be avoided.

While a response to the transmission line evaluation request is sent from the device B to the device A, data transmission by the devices A, B and other devices is prohibited or not to improve the throughput in the data transmission. 8 is a communication sequence when data transmission is not prohibited. Here, if data transmission is not inhibited, the response from device B is preferably given the highest priority.

Also, instead of the manner in which the receiving device B responds to the transmitting device A for sending the transmission line evaluation as described above each time, a plurality of transmission line evaluations are sent at once, or the receiving device B is based on the plurality of transmission line evaluations. Select the tone map, and notify the transmitting device A of the selected tone map. In each case, the effects of the present invention are not lost.

Second Embodiment

The first embodiment described above is a technique where the variation cycle of the characteristics of the transmission line is known in advance. Then, in the second embodiment below, a technique is described in which the optimum beacon period can be automatically set even when the variation cycle of the transmission line characteristic is not known in advance.

For example, the beacon period T1 when the fluctuation cycle L of the transmission line characteristic which the communication apparatus 1 tuned to the frequency of 60 Hz of a commercial power supply is 8.333 msec, and the integer n = 3 and m = 17 (FIG. 9). ) And a case in which the beacon period T (FIG. 10) can be set when the variation cycle L of transmission line characteristics tuned to the frequency of commercial power supply is 10 msec and the variables n = 3 and m = 17. have. In this case, the communication device 1 evaluates the transmission line in all the same sections within a beacon period and obtains a plurality of tone maps. 9 and 10 show transmission line evaluation section 2 (half-tone portion of the figure). The offset time is given by " L × k / n " (k is a real number satisfying 0 &lt; k &lt; m), and k = 16 in Figs.

Here, the frequency of the actual commercial voltage is 60 Hz.

As a result, the variation cycle L of the transmission line characteristic in the beacon period T1 further tunes with the noise tuned to the frequency (60 Hz) of the actual commercial voltage shown (FIG. 9). Therefore, in the transmission line evaluation section 2, the characteristics of the transmission line are substantially the same, and similar values for the communication parameter (PHY speed) of each tonemap can be obtained in the plurality of obtained tonemaps, and thus the beacon period T1 with respect to noise. And the correlation between the variation cycle L is judged to be high.

On the other hand, the variation cycle L of the characteristic of the transmission line in the beacon period T2 is not tuned to the noise tuned to the frequency (60 Hz) of the commercial voltage shown (Fig. 10). Therefore, in the transmission line evaluation section 2, the characteristics of the transmission line are different, and the communication parameter (PHY speed) of each tonemap is different for each of the plurality of obtained tonemaps. Therefore, it is determined that the correlation between the beacon period and the variation cycle L with respect to noise is low.

Based on the above points, the setting of the beacon period determined to have the highest correlation is most synchronized with the noise actually generated. Therefore, it is possible to automatically set the beacon period according to the variation cycle of the transmission line characteristic only when setting the beacon period so that it is highly correlated.

The optimal anti-noise communication parameter is selected by setting the beacon period according to the second embodiment and performing the process according to the first embodiment.

The embodiment described above can also be realized when the CPU executes a program that can execute the above-described procedure stored in the storage medium (e.g., ROM, RAM, or hard disk) to the CPU. In this case, the program is stored in the storage device through a storage medium and then executed, or directly in the storage medium. Storage media include semiconductor memories such as ROM, RAM, and flash memory, magnetic disk memories such as FD, HD, optical disks such as CD-ROM, DVD, BD, and memory cards. The concept of storage media also includes communication media such as telephone lines or carrier lines.

Each functional block indicated by a dotted line in FIG. 1 may be realized by an LSI as an integrated circuit. Each functional block may be formed as a single chip, one part or all over one chip. Although LSI is used in the embodiment, this circuit is called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

The integrated circuit forming method is not limited to using the LSI, and the circuit integration can be realized by a dedicated circuit or a general purpose processor. It is also possible to use field programmable gate arrays (FPGAs) that can be programmed after the LSI is created, and a reconfigurable processor that can reconfigure the connections and settings of the circuit cells inside the LSI.

In addition, if the circuit integrated technology is replaced by the LSI or switched to another technology by the development of semiconductor technology, it is natural that the functional block is integrated by the technology. For example, the application of biotechnology is possible.

Hereinafter, the present invention described in the embodiments will be described by applying to an actual network system. 11 is a diagram illustrating an embodiment of a network system to which the present invention is applied for high speed power line transmission. In FIG. 11, an IEEE 1394 interface, a USB interface, and the like installed in a multimedia device such as a PC, a DVD recorder, a digital TV, a home server system, and the like are connected to a power line through an adapter equipped with the functions of the present invention. With this configuration, it is possible to construct a network system in which digital data such as multimedia data can be transmitted at high speed through a power line as a medium. Compared to the existing wired LAN, the system does not require a new network cable, and it is possible to use a power line already installed in a home, an office, etc., thereby simplifying installation and providing convenience in terms of cost.

The embodiment described above is an example where an existing multimedia device is applied to power line communication through an adapter that converts a signal interface of the existing device into an interface of power line communication. However, in the future, the functions of the present invention may be included in the multimedia device, thereby enabling data transmission between the devices through the power code of the multimedia device. In this case, the adapter, IEEE1394 cable, or USB cable of FIG. 11 are not necessary, and wiring is simplified. It is also possible to connect to the Internet via a router or to connect a wired or wireless LAN using a hub, for example, so that it is possible to expand the LAN system using the high speed power line transmission system of the present invention. In the power line transmission method, communication data also flows through the power line. Therefore, compared with the wireless LAN, there is no problem of data leakage caused by the blocking of radio waves. The power line transmission method has a security effect of protecting data. Data flowing over the power line can be protected by IPsec of the IP protocol, by encoding the content itself, or by other DRM methods.

As described above, high quality AV is achieved by installing a QoS function including copyright protection by content encoding and by the effects of the present invention (flexible bandwidth allocation, addressing throughput improvement, increased retransmission, and traffic fluctuations). The content is transmitted over the power line.

The communication apparatus and transmission line evaluation method of the present invention are used, for example, in a communication system in which the characteristics of the transmission line change in a specific cycle, and for example, the characteristics of the transmission line need to be accurately evaluated so that data is transmitted and received at high throughput. Especially useful when there is.

Claims (10)

A communication device that performs periodic communication with another communication device through a transmission line, Set the communication period to "Lxm / n" (L is a variable cycle of transmission line characteristics, n is an integer of 2 or more, m is an integer of n or more, and the greatest common factor with n is 1). A communication control unit performing; A transmission line evaluator for evaluating the transmission line characteristics within a (L / n) time after the communication period starts and a specific offset time has passed; And And a communication parameter determining unit that determines a communication parameter used by the communication control unit based on the evaluation result of the transmission line evaluating unit. The method of claim 1, And the offset time is L × k / n (k is a real number satisfying 0 ≦ k <m). The method of claim 1, And said transmission line evaluator evaluates said transmission line characteristic at least n times. The method of claim 1, And said transmission line characteristic is evaluated when a detection of a change in state of said transmission line is first started. The method of claim 1, And said communication period is a period of beacons sent from a communication device functioning as a master unit. The method of claim 5, A time allocation request for evaluating the transmission line characteristic is sent to a communication device functioning as the master unit. The method of claim 6, The time allocation for evaluating the transmission line characteristic is notified from the communication device functioning as the master unit using a beacon frame or a polling frame, the transmission line characteristic is evaluated only during the time given the grant Communication device. The method of claim 1, The fluctuation cycle L of the transmission line characteristics is 1/2 of a commercial power cycle. In a transmission line evaluation method performed by a communication device that performs periodic communication with another communication device through a transmission line, Set the communication period to "Lxm / n" (L is a variable cycle of transmission line characteristics, n is an integer of 2 or more, m is an integer of n or more, and the greatest common factor with n is 1). Performing; Evaluating the transmission line characteristics within (L / n) time after the communication period begins and after a specific offset time; And And determining a communication parameter to be used in the step of performing the communication based on the evaluation result in the evaluating step. An integrated circuit used for a communication device that performs periodic communication with another communication device through a transmission line, Set the communication period to "Lxm / n" (L is a variable cycle of transmission line characteristics, n is an integer of 2 or more, m is an integer of n or more, and the greatest common factor with n is 1). A communication control unit performing; A transmission line evaluator for evaluating the transmission line characteristics within a (L / n) time after the communication period starts and a specific offset time has passed; And And a communication parameter determining unit that determines a communication parameter used by the communication control unit based on an evaluation result of the transmission line evaluating unit.

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